Return the cumulative sum of array elements over a given axis treating Not a
Numbers (NaNs) as zero. The cumulative sum does not change when NaNs are
encountered and leading NaNs are replaced by zeros.

Zeros are returned for slices that are all-NaN or empty.

New in version 1.12.0.

Parameters:

a:array_like

Input array.

axis:int, optional

Axis along which the cumulative sum is computed. The default
(None) is to compute the cumsum over the flattened array.

dtype:dtype, optional

Type of the returned array and of the accumulator in which the
elements are summed. If dtype is not specified, it defaults
to the dtype of a, unless a has an integer dtype with a
precision less than that of the default platform integer. In
that case, the default platform integer is used.

out:ndarray, optional

Alternative output array in which to place the result. It must
have the same shape and buffer length as the expected output
but the type will be cast if necessary. See doc.ufuncs
(Section “Output arguments”) for more details.

Returns:

nancumsum:ndarray.

A new array holding the result is returned unless out is
specified, in which it is returned. The result has the same
size as a, and the same shape as a if axis is not None
or a is a 1-d array.